1. Field of the Invention
The present invention relates generally to seafloor mapping systems and more particularly to such systems generating a stereo-film of the seafloor topography.
2. Description of the Prior Art
Various methods of seafloor mapping have been tried in recent years. Included in stereo-photo mapping of the seafloor by direct photography of the seafloor. Such systems exhibit limited effectiveness as they have a relative short underwater light sensing range.
U.S. Pat. No. 3,840,844 to the Applicant of the present application describes an electron beam analog technique for determining the X-Y-Z coordinates, in real time, of a seafloor target using two independently measured sonar-echo ranges as obtained by a pair of rotating, pulsed, side-looking sonar transducers, displaced from each other along a common vertical axis. The basic concept of this analog technique is utilization of the intersection of two circles, representing the respective wave fronts of the acoustic energy radiating cylindrically from the two sonar transducers. The intersection point is found in real time by means of a rastered electron beam; and the X-Y coordinates of the point are translated electronically to a PPI readout. The system of U.S. Pat. No. 3,840,844, however, is limited to determination of the coordinates of a single seafloor point in each aximuth sector of the scanned area.